Abrasive tool and method of making same



J, 20, 1942. BUCHMANN ABRASIVE TOOL AND METHOD OF MAKING SAME FiledSept. '21, 1939 I 2 1 zi. Q v ///////,///4 l7/////////4 INVENTOR [00/5Baa/202cm ATT RNEYS Patented Jan. 20, 1942 UNITED STATES PATENT OFFICELouis Buchmann, Buflalo, N. Y., assignor, by

mesne assignments, to Aln Cln, Inc., a corporation of New York AApplication September 21, 1939, Serial No. 295,941

11 Claims.

This invention relates to abrasive tools and to methods of making thesame.

In connection with the manufacture of abrasive tools employingindividual abrasive granules it has heretofore been conventionalpractice to provide the abrasive ingredient in grit form and of sizesdepending upon the nature of the work to be performed by the tool; andto bond the grit into the desired form of the tool by means of a bondingmedium of refractory or metallic substance. For example, in the case ofabrasive wheels employing diamond dust or grains it has been found to bedesirable to employ a metallic bonding medium which is as strong anddurable as possible in order to prevent loosening and loss of thediamond grains from the wheel prior to their full use as abrasive media.For this purpose various kinds of powdered metals and powdered metallicalloys have been employed, the abrasive grains being first mixedthroughout the powdered metal and the mixture then being sintered orfused under suitable conditions of temperature and pressure to form aconsolidated mass in the shape of the Wheel desired. Such methods,however, involve either homogenous or heterogenous mixing of theabrasive kernels throughout the bonding mass, and it is practicallyimpossible to provide a specially planned form of abrasive ingredient.distribution throughout the body of the wheel that is other than eitheruniform or heterogenous.

Thus, it is impossible under such prior methods to provide accuratelyplanned sectional distribution of abrasive ingredients in varyingconcentrations throughout the tool body, and, for

example, in the case of wheels having working faces of special shapesadapted to grind other than fiat surfaces the relatively inactiveportion of the wheels contain the same concentrations of abrasiv grit asdo the active portions thereof. Hence, whenever the wheel are redressedto proper cutting face form substantial losses of unused abrasive gritresults, and whenever the abrasive grit is of expensive nature, as inthe case of diamond grit, such losses are particularly undesirable.Also, it will be understood that since the abrasive grits aredistributed in equally concentrated form throughout the active andinactive sections of the wheel, the work of trimming away the unusedportions in connecslstance to structural strains under operatingconditions, and if the fusion process is not adequate to provide thenecessary structural strength the use of such wheel is uneconomical andfraught with danger.

One object of the invention is to provide an abrasive tool comprisingindividual abrasive grains and a bonding medium for uniting the wholeinto an integral structure of improved strength; the abrasive grainsbeing distributed throughout the structure in an improved manner and inaccord with a predetermined plan of arrangement.

Another object of the invention is to provide an improved abrasiv wheelof increased structural strength.

Another object of the present invention is to provide an improved methodof introducing the abrasive granules into the'bonding medium duringmanufactiireof abrasive tools.

Another object of the invention is to provide an improved abrasive wheelin which the abrasive ingredient thereof are distributed throughout thebody of the wheel in an improved manner and whereby the degree ofconcentratt on of abrasive granules is increased throughout thoseportions of the wheel that are called upon to provide th majority of thework-cutting action during service of the tool.

Another object of the invention is to provide an abrasive wheel whereinthe abrasive granular ingredient thereof are distributed throughout thebody of the wheel in such manner as to expedite and make more economicalthe redressing of the cutting face of the wheel subsequent tointermittent use thereof in an improved manner. Other objects andadvantages of the invention will appear from the specification herein.

In the drawing:

Fig. 1 is a section through an assembled structure preliminary'tomanufacture of a wheel of the invention;

Fig. 2 is a transverse section through the structure of Fig. 1;

Fig. 3 is a fragmentary view of one form of structural element of thewheel of the invention;

Fig. 4 is a view similar to Fig. 3 of another form of the samestructural element;

Fig. 5 is a fragmentary section of a strip element of the structure ofthe invention showing abrasive grains applied thereto by means of atemporary bonding medium;

Fig. 6 i a section corresponding to Fig. 2 of another form of theinvention;

Fig. 7 is a diagrammatic view in section of a step of the process ofmanufacturing the wheel of Fig. 6; and

Fig. 8 is a section similar to Figs. 2 and 6 of another form of wheelof.the invention.

In practicing the invention, the abrasive grits to be employed areunited with a novel form of bonding medium which is made up byassembling in laminated manner sheets of the bonding material. Forexample, a illustrated in Fig. 1, a wheel of the invention is shown ascomprising a metallic core l around about the periphery of which hasbeen wound a metallic strip I2 to provide a plurality of layers, thenumber of which depends upon the desired depth of the working portion ofthe wheel. As illustrated in Figs. 3 and 4, the metallic strip I! may beeither of meshed wire fabric form (Fig. 3) or of strip metal formprovided with minor perforations or indentations l (Fig. 4), or in anyother suitable form to provide the features hereinafter described.

The abrasive granules for the wheel are positioned upon the metallicstrip 12 prior to the wrapping of the strip about the core It! byspreading a supply of the loose granules across the strip I2, duringwhich operation the interstices of the wire mesh of Fig. 3 or theindentations of the strip of Fig. 4 will receive individual abrasivegrains in embraced relation therein. The spreading and adhesion of theabrasive grains upon the strip I2 may be facilitated by first mixing thegrains in a plastic carrier such as some neutral oil or grease or otherliquid or semi-liquid substance that will provide a temporary bondbetween the abrasive grains and the strip to prevent dislodgment of thegrains from the strip during the process of wrapping the strip about thecore l0. Fig. 5 illustrates such application of abrasive grains It tothe pockets l5 by means of a plastic carrier l8. Preferably, the graincarrier substance will be of some chemically neutral form of grease oroil or the like that will evaporate or otherwise become dispelled duringthe subsequent processes of the invention without deleterious efl'ectsupon the finished structure. To assist in connection with the startingof the process of winding the strip l2 about the core I 0 a slot l I(Fig. 1) may be formed in the periphery of the core to receive an endportion of the strip and to hold the latter against sliding movementrelative to the core during the winding process. Upon completion of theprocess of winding the strip about the core [0, the wheel is placed in afurnace and/or otherwise subjected to an elevated temperature at aboutthe degree of initial fusion of the metal of the strip l2 for a lengthof time sufiicient to provide thorough welding of adjacent portions ofthe grit-carrying strip without allowing the bulk of the metal thereofto become so fluid as to allow the impounded abrasive particles to moverelative to the mass. In some cases, an application of pressure upon thestructure during the heating process will also be beneficial and ofassistance in providing a thorough welding. Thus, a rugged weldedstructure is provided wherein the metallic binding portions thereof areessentially of structurally undisturbed form but welded together into anintegral mass, thus avoiding burning or other deleterious action withrespect to the metal of the structure. This provides a wheel of greaterstructural strength as compared to the so called sintered wheel of theprior art which are made by fusing powdered metallic mixtures. In thecase of such sintered types of wheels the finished product is ofcrystalline-like structural form and resembles in appearance a crustymass of granules adhering to one another by reason only of intermittentand spaced points of welded contact, and the mass is usuallyinterspersed with a multitude of minor voids. Thus, the abrasive grainsare at best only partially surrounded by and attached to the bondingmaterial. In order to avoid deleterious eflects upon the abrasive grainsubstance it is necessary to limit the sintering heat to as low atemperature as may be possible to obtain adhesion between the grains;and it is difiicult in such cases to obtain complete sintering of themass without overheating portions thereof. Consequently, the finishedproducts of such methods are usually non-uniform as to structuralstrength and often 7 and therefore, even though the fusion process ofthe method of the present invention may not in some instances be carriedout to perfection between all of the adjacent surface portions thereof,the tool will nevertheless be reenforced throughout by the unalteredintegral solid metallic bodies. Thus, in no case will the tool of theinvention be subject to disruption under stress in the manner ofsintered wheels, or the like. In the case of production of tools of thepresent invention in the form of abrasive wheels as illustrated in Figs.1 and 2 of the specification, it will be seen that the laminated stripstructure l2, upon being welded together provides a wheel that ispositively reenforced circumferentially against centrifugal and/or otherforces which tend to disrupt it during use.

The avoidance of conditions of fluidity in the metal of the structureduring the fusion process precludes the possibility of redistribution ofthe abrasive grains in the mass and/or undesirable segregation thereofas would otherwise occur under conditions of mass metal fluidity; andthe planned distribution of abrasive particles throughout the wheel massis accordingly obtained in the finished product. As illustrated inbroken lines in Fig. 2, the wheel may be dressed to the form of aV-shaped groove cutting wheel,

or into any other special form by means of any suitable dressingoperation. For example, the peripheral face of the wheel, instead ofbeing flat as shown in Fig. 2, may be subsequently dressed to concave orconvex form, or into any other special shape as may be required inconnection with the cutting of stock in the various industries to whichthe use of an abrasive wheel may be applied. Also, it is contemplatedthat the strip I! may be bent or dished or otherwise deformed in anydesired manner before being wrapped around the core l0 so as to providean interlocking laminated structure in which the sectional elementsthereof are other than flat as illustrated in Fig. 2.

. It is contemplated that various kinds of abrasive granules may beemployed in connection with the method of the invention and that thesizing of the abrasive granules will be regulated as desired and inaccordance with the character of the work to be done by the wheel. Also,it is contemplated that the strips I! may be formed of a variety ofsuitable materials such as any of the well known fusible metals and/ormetallic alloys and/or noumetallic materials, according to the type ofbonding connection that is desired between the adjacent layers' and theabrasive grains. It is also contemplated that the heat of the fusingoperation may in some cases be limited in such manner that only partialfusion of the adjacent metallic body elements takes place, and that insuch case a section taken through the tool transversely of.the planes ofthe lamina thereof will reveal that the internal structure appears toindefinitely bear resemblance to the prior laminated structural form. Onthe other hand, the fusion process may be carried out to such extentthat all evidence of the original laminated structural form will havedisappeared, and in such case a section taken in any direction throughthe finished product will reveal simply a homogeneous, dense, coalizedmetallic mass in which are interspersed the abrasive particles in accordwith the predetermined plan of their relative arrangement therein.

It is also contemplated that in connection with the initial depositionof the abrasive granules upon the strip I2 any suitable means foraccomplishing the desired distribution may be employed, and that in lieuof the oily or greasy carrier referred to hereinabove, any other form ofpaste or liquid may be employed, or that the abrasive grains may simplybe dusted into the interstices of the strip without the use of anycarrier substance.

Whenever the stock to be operated upon by the wheel is not initiallyshaped complementary to the shape of the wheel cutting face, thatsection of the wheel that is called upon to do the maj ority of the workwill preferably be provided with an increased concentration of abrasivekernels as compared to the other portions of the wheel. To obtain suchan arrangement of abrasive kernel concentration, the strip I! may beprovided with an increased number of grain receiving depressions in theregion of the desired increased grain concentration, and when thediamond or other abrasive grits are dusted or painted upon the surfaceof the strip they will embed themselves in the strip according to thepredetermined plan of uneven arrangement. For example, as illustrated inFig. 4, an increased number of depressions l5 are provided in thecentral portion of the strip I2, and when the abrasive grain substanceis applied thereto a larger number of grits per unit of area will becomeembedded in the central portion of the strip as compared to the sideedge portions thereof. Hence, when the strip I2 is wound about the coreIll and fused into place thereon the central section of the wheel willbe richer in abrasive grit as compared to the side portions thereof.Consequently, the abrasive grit is employed in accurately controllablemanner, and wasteful employment of abrasive kernels in the relativelyinactive portions of the wheel is avoided thus effecting substantialeconomies whenever the abrasive kernels are of the expensive type suchas diamond dust or the like. Also, it will be seen that because of thefact that the relatively inactive portions of the wheel are of reducedabrasive character, the process of redressing the wheel after the designof the cutting face has been deformed will be less difilcult and willinvolve less loss of valuable abrasive material.

It will be seen that the desired kind of abrasive distributionthroughout the wheel section may be obtained in ways other thanhereinabove described in connection with preparation of the strip II.For example, in lieu of the use of an increased number of depressions I!at the center of the strip, a strip of uniformly deformed character maybe employed and the abrasive grits may be applied thereto in such manneras to give the desired form of grain distribution. Thus, in connectionwith the preparation of a wheel as illustrated in Fig. 2, the coating ofabrasive carrying substance which is applied to the strip preparatory towinding thereof about the core may be of increased thickness along thecenter line of the strip; or, the strip may be painted by multipleoperations involving the application of a mixture along the center lineof the strip that contains a higher percentage of abrasive to thecarrier employed as compared to the percentage of abrasive to thecarrier employed in connection with the painting of the side edgeportions of the strip.

In any case it will be seen that the object is to locate the abrasivekernels in accord with a predetermined desired manner of distributionthroughout the wheel body by temporarily impounding the abrasive kernelsin the component elements entering into the assembly of the abrasivewheel and subsequently fusing the elements thereof together into aunitary mass of high structural strength without substantiallydisturbing the distribution and relative concentration of the abrasivekernels throughout different portions of the wheel mass. Thus, it willbe seen that in lieu of the spaced point type of depressions I5illustrated in Fig. 4, the strip l2 may be prepared in any other desiredmanner to provide a multiplicity of interstices throughout the surfaceor body thereof for receiving and retaining therein the abrasive kernelsin accord with a previous plan of distribution. For example, theabrasive receiving interstices of the strip I2 may be provided by anyform of embossing, knurling, scratching, serrating, or other actionwhereby suitable forms of abrasive grain holding pockets are provided.

As explained hereinabove, the wire mesh of Fig. 3 will similarly providea preferred form of strip l2 because of the shape of the abrasivereceiving interstices which are provided between the wire strands, andvarious types of abrasive concentration patterns may be obtainedthroughout the wheel section made from such wire mesh by varying thedimensions of the wire strands and/or of the spacing therebetween, or bypainting a uniform type wire mesh strip with pastes of differentconcentrations or with different thicknesses of an abrasive paste atdifferent portions thereof.

Fig. 6 illustrates another form of the invention wherein a wheelstructure comprises a series of discs 30 which are generally of thecharacter of the strips l2 of Figs. 3 or 4 and disposed in sideby-siderelation and pressed and fused together to form a unitary mass in thedesired form of the abrasive wheel. The discs 30 may be either of wiremesh form as explained hereinabove or they may be in the form ofdeformed sheets, knurled or scratched or otherwise treated to provideabrasive retaining pockets therein. As in the form of the invention ofFigs. 1 through 4, the discs 30 are coated with abrasive kernels in thepredeter mined desired manner of distribution and/or relativeconcentration in any given case, and the discs are then subjected tofusing temperatures and pressures as provided for by opposed die devices35 and 36 (illustrated diagrammatically in Fig. '7). In order to providethe abrasive ingredients in concentrated form in the regions of the mostactive working portions of the wheel, the individual discs ultimatelygoing into the makeup of the most active working portions of the wheelwill preferably be coated with increased concentrations of abrasive ascompared to the discs going into the make-up of the relatively inactiveportions of the wheel. Thus, in connection with the manufacture of aV-shaped groove cutting wheel as illustrated in Fig. 6, the center discs30 will be initially coated with greater quantities of abrasive kernelsthan are the discs at the opposite side portions thereof. The ridge-likeperipheral form of the wheel may be obtained either by providing thediscs 30 of different and appropriate diameters whereby the building upof the laminated structure will automatically provide the approximateform desired and avoid waste of expensive abrasive grains, or by usingdiscs of equal diameters and dressing the wheel to desired formsubsequent to the fusion process.

Fig. 8 illustrates another form of the invention wherein an abrasivewheel of the general type of the wheel illustrated in Fig. 6 is providedwith a central reinforcing core 40. The core may be a disc of solidsteel or other suitable metal, and abrasive carrying discs 42 of thetype hereinabove described in connection with the construction of thewheel of Fig. 6 are pressed and fused about the core and into the formof a unitary mass, the peripheral edge portions of the discs beingarranged to extend beyond the edge of the core and to be pressed andfused together during the manufacturing process whereby an abrasiveperipheral working edge will be provided. It will be understood that theworking edge may be formed to the desired shape by means of subsequentdressing operations or by initially providing the discs 42 of suchdiameters as to combine to give the desired edge form when pressed intofinal position, or by any other suitable method.

It will be understood that in lieu of the speciflc method of wrappingthe coiled strip l2 about the core I, as illustrated in Figs. 1 and 2and as explained hereinabove, the annular body of abrasive containingmaterial thereof may be initially assembled apart from the core l andcompacted and fused into solid integral form and then mounted upon thecore element ill in accord with any suitable shop practice such as bywedging, soldering, or the like; and in such case the core It need notbe subjected to the fusing temperatures as hereinabove described.

It will be understood that the invention is applicable with equalfacility to the manufacture of a large variety of abrasive tool shapessuch as are suitable for use in connection with a multiplicity ofindustries, and that although only a limited number of the forms of theinvention have been shown and described in detail herein, variouschanges may be made therein without departing from the spirit of theinvention or the scope of the appended claims.

I claim:

1. The method of manufacturing an abrasive tool comprising essentiallythe steps of providing metallic sheet stock of perforated form withabrasive grains in the interstices thereof, arranging said abrasivecarrying stock into a body of laminated contiguous sheet form, andheat-fusing adjacent portions of said sheet stock together.

2. The method of manufacturing an abrasive tool comprising essentiallythe steps of mounting abrasive granules in the interstices of a seriesof metallic wire mesh sheet elements, arranging a plurality of saidmetallic wire mesh sheet elementsinto a body of laminated contiguoussheet form, and heat-fusing contiguous elements of said laminatedstructure together to form aunitary mass.

3. The method of manufacturing an abrasive tool comprising the steps ofarranging in plurality of separate perforated metallic sheet elementsinto a body of laminated contiguous sheet form, said sheet elementshaving mounted in the interstices thereof abrasive granules in accordwith a definite plan of abrasive granule distribution whereby theconcentration of abrasive granules is increased progressively from onesectional zone of said body to another sectional zone thereof, andheat-fusing the adjacent sheet element portions together to form aunitary mass.

4. An abrasive tool comprising laminae of metallic mesh material havingabrasive mounted within the mesh thereof and secured into an integralstructure by sintering.

5. An abrasive tool of sintered metallic body form comprising foraminousmetallic laminae having abrasive grains mounted in th intersticesthereof.

6. An abrasive wheel comprising a core and an abrasive portion integralwith and disposed peripherally of said core, said abrasive portion beingcomposed of a coiled strip of sheet metal material having pocketsdisposed therein in accord with a predetermined plan of pocketdistribution whereby the concentration of said pockets increasesprogressively from one sectional zone of said strip to another sectionalzone thereof, abrasive grains mounted in said pockets, said coiled stripbeing sintered into a unitary structure with said abrasive grains lockedtherein in accord with said predetermined plan.

7. An abrasive wheel in the form of a laminated structure comprisingseries of sheet metal disc elements in contiguous superposed relation,said disc elements having pockets therein disposed in accord with apredetermined plan of arrangement whereby the concentration of saidpockets increases progressively from one sectional zone of said abrasiveportion to another sectional zone thereof, abrasive grains mounted insaid pockets. said disc sheet elements being sintered together into theform of a solid structure with said abrasive grains disposed therein inaccord with said predetermined plan.

8. An abrasion tool comprising a coiled strip of sheet metal materialhaving. pockets disposed therein in accord with a predetermined plan ofpocket distribution whereby the concentration of said pockets increasesprogressively from one sectional zone of said strip to another sectionalzone thereof; said strip having abrasive grains mounted in said pockets,and said coiled strip being sintered into a unitary structure with saidabrasive grains locked therein in accord with said predetermined plan.

9. An abrasion tool comprising series of sheet metal disc elementsarranged in contiguous superposed relation, said disc elements havingpockets therein disposed in accord with a predetermined plan ofarrangement whereby the concentration of said pockets increasesprogressively from one sectional zone of said abrasion tool to anothersectional zone thereof, abrasive grains being mounted in said pockets,said disc sheet elements being sintered together into the form of asolid structure with said abrasive grains disposed therein in accordwith said predetermined plan. e

10. The method of manufacturing an abrasive tool comprising the steps ofarranging in association with a surface portion of a foraminous metallicstrip element means for temporarily mounting in fixed relation withinthe foramina of said strip element abrasive granules in ac cord with adefinite plan of abrasive granule distribution whereby the concentrationof said granules increases progressively from one sectional zone of saidstrip element to another sectional zone thereof, coiling said abrasivemounting strip to provide a wheel structure, and sintering said wheelstructure into a unitary metallic body with said abrasive granuleslocked by sintered metal therein in accord with vsaid definite plan ofabrasive granule distribution, said granule mounting means being of suchcharacter as to be eliminated upon sintering of said structure.

11. The method of manufacturing an abrasive tool comprising theproviding in association with surface portions of metallic foraminouslaminae means for temporarily supporting in fixed relation within theforamina of said laminae abrasive granules in accord with a definiteplan of abrasive granule distribution whereby the concentration of saidgranules varies with respect to difierent of said laminae, arrangingsaid disc elements into the form of a.single laminated structure withsaid abrasive granules temporarily supported by said means therewithin,and sintering the metallic portions of said laminated structure togetherso as to provide a unitary body with saidabrasive granules locked bysaid sintered metallic portions therewithin in accord with said definiteplan of abrasive granule distribution, said granule supporting meansbeing of such character as to be eliminated upon sintering of saidstructure.

LOUIS BUCHMANN.

